Automatically-operated pick-up switch



A ril 29, 1930. W. FJCOTTER 1,756,815

' AUTOMATICALLY OPERATED PICK-UP SWITCH Filed Sept. 11, 1928 2 Sheets-Shem 1 o AUDIO AMPUFIE l WILLIAM F COTTER, IO INVENI'OR ATTORNEY April 29, 1930. w, F, co 1,756,815

AUTOMATICALLY OPERATED PICK-UP SWITCH Filed Sept. 11, 1928 2'She8ts-Sheec 2 INVENTOR Mum/v f7 C0TrR ATTORNEY Patented Apr. 29; 1930' v UNITED sT-Aes ,WILLIAM F. coz'rrnn, or SPRINGFIELD, massacriusn'rrs, AssreNoa r mnzarclm. BOSCH mennro conronn'rron, or srnmerrnnn, -massacnusn'rrs, A CORPORA- TION OF NEW YORK.

nu'roimr'IQAnLY-orsnnrnn rrex ur swrrcn Application-filed September 11, 1928. Serial No. 805,289.

This invention relates to systems for amplifying sound,and more particularly to systems for the amplification of phonographically recorded sounds through thermionic or electronic means. 4

A practical object of this invention-is to provide means for automatically connecting an electromagnetic or phonographic pickup or circuit to the audio-frequency amplifier of a radio receiver, said means being preferably adapted to simultaneously disconnect the amplifier fr m the detector when .said pickup is connected to saidamplifier. The purpose of disconnecting the amplifier from the detector is to prevent static and electrostatic noises, as well as harmonics and heterodyne squeals and whistles, from passing into the amplifier when the pickup is in operation. The said means. comprises, preferably, a switch which is operated automatically when one of the members of the tuning means of said receiver (the condenser drive wheel or drum, for example) is rotated or moved beyond the tuning range, or at any predeterminedpoint in its rotation. p 7

In the event the tuning means are variable inductances then the moving parts of said inductances maybe employed to operate said switch. v I I The invention is," of course, broader in scope than the example here cited, since the invention has application in many other ways i which are within tlfli principle thereof.

The invention is, broadly,'th e combinationwitha movabletuning member of a switch adapted to be operated at a predetermined point in the movement of said member, whetherv said switch is operated to connect a pickup, connect or disconnect other circuits, or combinations of said operations.

The 'accompanying'drawing, therefore, 11 lustrates one of the. many possible embodiinents of my invention.

Fig. 1 is acircuit diagram of a radio receiving circuit having a switch automatical- 1y operable by the movable ortuning member of a-condenser; Fig. 2 is similar to Fig.

, 1 showing the switch closed Fig. 3 is a modification of :liwherein is substituted a single pole don 1e throw switch for the .3 or a single pole double throw switch 13,

mally disconnectedand the detector is always single pole throw switch of Figs. 1 and 2; Fig. 4 is a top view of a rotatable drum with which is associated the switch of 3; and Fi 5 is a side view thereof.

eferring to Fig. 1, there is shown part of a radio receiving and amplifying circuit. In order to connect the electromagnetic or phonographic pickup 1 to the audio frequency amplifier 2 of the receiver,there is provided a single pole single throw switch which is disposed adjacent the.drum 4 (Fig. 4) mountedon the shaft 5 of a condenser 6. Attached to the side of the drum is an insulating strip or. lug 7 over which isadapted to open or close switch 3 as the case may be.

' The said strip 7 is placed on said drum at such a point thatat apredetermined point in its rotation it shall operate said switch; preferably said strip is placed on said drum beyond the tuning range, say below zero, to close said switch when the drum is rotated. beyond said range. I Insaid circuit the switch has the arm 8 connected to the plate 9 of the detector tube 10-and to one of the pick-up terminals 12, 12, and the other arin llof said switch is connected to the other terminal 12, which may be grounded. The electromagnetic pickup 1 is adapted to be connected to said terminals and hence to the amplifier 2.

It-will be observed that in the arrangement shown in Fig. 1, the switch is so arranged that the pickup circuit to the amplifier is norconnected to the amplifier, but the switch may be arranged as shown in (Fig. 2).. It is not desirable when employing the pickup to have the radio frequency side of'the receiver connected tothe audio amplifier since to do so introduces into the reproduction static and other interfering noises. I prefer therefore to disconnect the plate of the detector from the amplifier when the pickup is in o eration, in substantially the same manner above de- 95 scribed. That is, instead of the switch being normally open, it is normally closed (for radio operation, Fig. 2), and when it is desired to use the pickup to arrange to haye the lug 7 on the drum to open said switch so as to 1 disconnect the detector and since in this case (Fig. 2) the pickup circuit is always connected, the pickup will, of course, be connected.

It will he understood'that, in the caseof Fig. 2, when the receiver is in operation, the pickup is disconnected from the switch. The reason for this is that the low impedance of the pickup unit shunts the audio frequency system with the result that the energy from the detector is by-passed to ground.

The switch is therefore arranged to he opened when the drum is turned below zero or beyond the tuning range of the condenser so as to disconnect the detector circuit from the amplifier, the amplifier being permanently connected to the pickup circuit as shown in Fig. 2.

Instead of employing a single pole single throw switch as above indicated, I may use a single pole double throw switch 13 shown in Fig. 3. Said switch 13 is provided with two stationary contacts 14 and 15 and a movable contact arm 16.

' The arm 14 is connected to the plate 9 of the detector, while the other stationary contact 15 is connected to the pickup. The movable arm 16 is connected to the primary 18 of the first audio frequency transformer 19 of' the thermionic amplifier.

By this arrangement either the plate or the pickup may be arbitrarily connected to the amplifier, but said switch is operated in substantially the same manner as the others.

. Having thus described my invention, what I claim is: v

1. The combination with a'radio receiver having a tunable circuit connected to an circuit, and a switch in the plate circuit of the detector operable by said tuning means to connect said pickup circuit to and disconnect said detector from said amplifier.

4. The combination with a radio receiver having a tunable circuit, tuning means therefor, andan audio-frequency amplifier, of a phonograph pickup, and a switch arranged to be operated by said tuning means to connect said pickup to said amplifier when said tuning means is moved beyond the tuning ran e.

5. The combination with a radio receiver audio-frequency amplifier and to'connect said pickup to said amplifier.

6. The combination with a radio receiver having tuning means and an audio-frequency amplifier, of a phonograph pickup circuit, and a switch operable by said tuning means to connect said pickup circuit to said ampli-' fier when said tuning means is moved beyond the tuning range.

7. The combination with a radio receiver having tuning means. a detector and an audio-frequency amplifier, of a phonograph pickup circuit, and a switch in the plate circuit of the detector operable by said tuning means to connect said pickup circuit to and disconnect said detector from said amplifier, when said tuning means is moved beyond the tuning range.

8. The combination with a phonograph pickup circuit, of a thermionic amplifier circuit, a switch between said pickup and amplifier circuits, a tuned circuit,a rotatable tuning member, and means thereon adapted to operate said switch when said member is moved beyond the tuning range.

9. The combination with a phonograph pickup circuit, of a thermionic amplifier circuit. a switch connecting the pickup circuit to the amplifier circuit, radio-frequencyand detector circuits, a rotatable'tuning member, and means thereon adapted to operate said switch, when said member is moved beyond the tuning range, to disconnect the radiofrequency and detector circuits from and connect the pickup circuit tothe amplifier circuit.

10. The combination with a radio receiver having radio-frequency, detector and amplifier circuits, of a rotatable tuning member, a switch, a phonograph pickup circuit, and means on said member adapted to operate said switch when said member is moved beyond the tuning range, to disconnect the radio-frequency and detector circuits from and connect the pickup circuit to the amplifier circuit.

11. The combination with a radio receiver having rotatable tuning means, a tuned detector circuit and an audio-frequency amplifier, of a phonograph pickup circuit, and a switch in the plate circuit of the detector operable by means on said tuning means, when said tuning means is moved beyond the tuning range, to disconnect the tuned circuit from and connect the pickup circuit to the amplifier.

In testimony whereof I afiix my signature.

WILLIAM F. CUTTER. 

